The present invention relates to a wireless communication device and a connection request transmission power control method, and particularly relates to transmission power control in the wireless communication device when initiating a communication.
In a CDMA (code division multiple access) system wireless communication system, an access packet (connection request) is transmitted from a mobile station to a base station, and acknowledgement (ACK) is returned from the base station to the mobile station in response to this transmission so that the wireless communication between both the stations is initiated. Here, the transmission power of the access packet is first determined by open loop control on the mobile station side. Namely, a pilot signal is received from the base station in the mobile station, and the transmission power is determined on the basis of this received power. If the access packet is transmitted using the power thus determined and no acknowledgement in response to this access packet is received in the mobile station, the transmission power is increased by a power amount designated from the base station side, and the access packet is retransmitted. Thus, the base station can reliably receive the access packet transmitted from the mobile station. For example, a similar wireless communication system is disclosed in JP-A (Japanese Laid-Open Patent)-08-307344.
In the above system of the background art, the power is increased by a constant power amount designated from the base station side when retransmitting the access packet. Accordingly, there is a possibility that the power is uselessly consumed and connection time is increased. Namely, when the increase in transmission power is small, the retransmitting of the access packet is again performed. In this case, the connection time is lengthened and the consumed power is increased. Further, when the increase in transmission power is large, the acknowledgement is easily obtained, but power is needlessly consumed.
Further, in the above system of the background art, the transmission power when the access packet is transmitted the first time is merely determined by the open loop control and interference amount information in the base station is not taken into consideration. Therefore, in accordance with situations of the interference amount in the base station, there is a case in which no response (acknowledgement) is obtained from the base station in response to the transmission of the access packet. In this case, a problem exists in that the retransmitting of the access packet is obliged.